The study of sublethal effects of toxicants on hematological
parameters, enzymes activity and intermediary metabolites can reveal
the state of fish health and can be used to measure possible
environmental impacts [6,12]. One of the organophosphorus pesticides
(OPs) classic effects on animals is acetylcholinesterase (AChE)
inhibition. This occurs when their active derivatives (oxons) are
activated, thus forming a enzyme–inhibitor complex [3,6,24]. The
acetylcholinesterase inhibition damages the nervous impulse
transmission and therefore the functioning of the whole nervous
system [6]. These effects can result in metabolic disorders which
are reflected in changes in oxygen consumption and ammonia
excretion